Lesson 1 of 86 min read
What the cloud means for a tester
Most applications you test today run in the cloud: on servers rented from Amazon (AWS), Microsoft (Azure) or Google (GCP) instead of machines in the company office. You don't need to be a cloud engineer, but you do need to know what is running where, so you can find bugs, read logs and explain failures. This lesson explains the cloud in plain words.
Key takeaways
- 1The cloud is computing (servers), storage and services rented on demand over the internet and created or removed in minutes.
- 2Three service levels: IaaS (you rent virtual machines), PaaS (you deploy code, the provider runs servers), SaaS (finished software such as email or Jira).
- 3Regions and availability zones: a region is a geographic area (for example Mumbai); zones are separate data centres inside it. Apps spread across zones to survive failures.
- 4Everything is created by configuration or code, so test environments can be created and destroyed on demand instead of shared forever.
- 5For testers: more moving parts (services, queues, functions), more places for bugs, and more logs and metrics to help you find them.
One shop app, mapped to cloud pieces
User's browser | v CDN (static files, images) | v Load balancer -> App servers / containers (2 zones) | | v v Managed database Object storage (invoices, photos) | v Queue -> Serverless function (send email) Each box is a separate cloud service with its own settings, logs and ways to fail.
Go deeper
Expert notes beyond the basics
- 01
Shared responsibility
The provider secures the data centres, hardware and the services themselves. The customer is responsible for how they configure them: who has access, whether storage is public, which ports are open and how data is protected. Most cloud bugs and incidents testers find are on the customer side of that line.
- 02
Why zones matter in testing
Apps run in two or more availability zones so one data-centre failure doesn't take them down. That means several copies of a service can be running different states at the same moment, which explains bugs like 'refresh shows old data' when caches or replicas are briefly out of sync.
- 03
Managed services change what you test
With a managed database or queue, you don't test the provider's software itself. You test your app's use of it: configuration, limits, timeouts, permissions, and behaviour when the service is slow or unavailable.
Common mistakes to avoid
- - Thinking the cloud is just 'someone else's server' and ignoring service boundaries.
- - Assuming the provider handles security settings such as public storage access.
- - Testing only the UI and never checking which service actually failed.
- - Using production as the only realistic environment.
Try it yourself
Draw (in text) the cloud pieces behind an app you use daily, such as a food delivery app, and list one test idea for each piece.
Write your answer on paper or in a sheet first, then compare.
Interview questions
How to answer like a confident QA engineer
- Q1
Why should a QA engineer understand cloud basics?
Model answer
Because the system under test is usually spread across cloud services: load balancers, containers, managed databases, storage, queues and serverless functions. Knowing these pieces lets me design tests for the boundaries between them, reproduce environment-specific bugs, read logs and metrics during investigation, and give developers a precise bug report naming the service and region that failed, instead of 'the site is broken'.
- Q2
Explain IaaS, PaaS and SaaS with an example each.
Model answer
IaaS: renting virtual machines such as AWS EC2, where you manage the OS. PaaS: deploying code to a platform such as Azure App Service, where the provider runs the servers. SaaS: using finished software such as Jira or Gmail.
- Q3
What is the shared responsibility model?
Model answer
The provider secures the underlying infrastructure; the customer secures their configuration, data, identities and access. A public storage bucket is the customer's mistake, not the provider's.
Knowledge check
+5 points
What is a cloud region?